In semiconductor industry, fabrication of semiconductor devices requires deposition of multilayer thin films. When the multilayer thin films are deposited, with an increase in the number of the layers, a high degree of surface planarity is necessary because any surface unevenness or imperfection will be gradually magnified, which affects the manufacturing yield and long-term reliability of the semiconductor devices. Thus, a planarization process is performed on each thin film layer of the semiconductor devices so that each thin film of the semiconductor devices may have a flat surface.
Since 1980s, Chemical Mechanical Polishing (CMP) processes have been used in the semiconductor industry. The CMP process may solve the problem caused by the unevenness of each thin film layer surface of the semiconductor devices generated by the combined effect of chemical grinding and mechanical grinding.
A conventional CMP process is performed on a semiconductor device as follows:
Referring to FIG. 1, a device layer 105 including a metal layer 103 and an insulating layer 101 is provided, the device layer 105 having a surface that is grinded by using an acid grinding slurry 110. While the layer 105 is being grinded, benzotriazole (BTA) is added to prevent the layer 105 from being oxidized. After grinding the polishing layer 105 is finished, a residual layer 111 is formed on the surface of the device layer 105, which includes a metallic oxide and/or metallic hydroxide 107, a BTA 109 and the grinding slurry 110 adhering to a surface of the metallic oxide and/or metallic hydroxide 107.
Referring to FIG. 2, the residual layer 111 is removed by deionized water.
However, while the residual layer 111 is being removed by the deionized water, a part of the metallic oxide and/or metallic hydroxide 107, and the BTA 109 adhering to the surface of the metallic oxide/hydroxide 107 and the like are difficult to be removed. These remaining residues greatly affect the manufacturing yield and long-term reliability of the semiconductor devices.
Accordingly, the device layer may have an uneven surface due to the metallic oxide, metallic hydroxide that are left on the surface of the device layer, and corrosion inhibitor adhering to the surface of the metallic oxide, metallic hydroxide. Therefore, there is a need to provide a CMP method that is capable to remove the residues and provide a flat surface of the device layer to increase the manufacturing yield and long-term reliability of the semiconductor device.